1. Field of the Invention
The invention relates to switching of both telephony data and packet data within a telecommunication switching system, and to converting data between a telephony data format and a packet data format.
2. Discussion of the Prior Art
FIG. 1 illustrates a plan view of a prior art system for converting data between a telephony data format and a packet data format. A microprocessor 1 running appropriate software converts data from pulse-coded modulation (PCM) data format to Internet protocol (IP) data format. This prior art system is slow and processes a limited number of calls because of all of the functions of converting the data performed in software.
FIG. 2 illustrates a plan view of a prior art system for converting data between telephony and packet data formats. The system comprises a microprocessor 1 and a digital signal processor (DSP) 2. The coder-decoder (CODEC) function of the conversion routine is no longer performed by the microprocessor 1, as in FIG. 1, and is instead performed by the DSP 2. The DSP 2 converts data between PCM data format and packet data format. Running appropriate software, the microprocessor 1 converts data from packet data format to IP data format. Although this prior art system is faster than the prior art system of FIG. 1, this prior art system suffers from an inability to handle a significantly large number of telephone calls. The conventional prior art system is discussed in Eric Baer, xe2x80x9cDesigning an Embedded Voice over Packet Network Gateway,xe2x80x9d Communication Systems Design, pp. 21-27, Oct. 1998. Conventional prior art systems offered for sale include: the Alliance Generation-8/80 Board (AG-8/80) by Natural MicroSystems of Framingham, Mass., which can only handle eight voice channels; the Alliance Generation-T1 Board (AG-T1) by Natural MicroSystems of Framingham, Mass., which can only handle twenty-four voice channels; the Fusion IP Telephony Development Platform by Natural MicroSystems of Framingham, Mass., which can only handle eight voice channels; and the VocalTec Telephony Gateway by VocalTec Communications Ltd. of Herzliya, Israel, which can only handle twenty-four voice channels.
An object of the invention is to provide a telecommunication system for interfacing between a telephone network and packet data network.
An object of the invention is to provide a transcoder for converting data between a telephony data format and a packet data format.
An object of the invention is to provide telephony-to-packet data format conversion and packet-to-telephony data format conversion having low jitter and low latency.
An object of the invention is to provide a single transcoder board capable of processing a large number of channels, such as over a thousand channels.
The invention includes an a transcoder for converting data between a telephony data format and a packet data format. The transcoder comprises: a digital logic telephony data engine receiving telephony data for the transcoder and transmitting telephony data for the transcoder, the digital logic telephony data engine including a frame accumulation buffer; a digital logic packet engine receiving packet data for the transcoder and transmitting packet data for the transcoder; a digital signal processing complex coupled to the digital logic telephony data engine and the digital logic packet engine, the digital signal processing complex comprising an array of digital signal processors; and a host processor coupled to the digital logic telephony data engine and the digital logic packet engine, wherein the digital logic telephony data engine, the digital logic packet engine, and the digital signal processing complex perform media channel processing, wherein the host processor performs control channel processing.
The invention includes a system for connecting a telephone network and a packet network. The system comprises: a hybrid switch coupled to the telephone and packet networks switching data between the telephone and packet networks; and at least one transcoder coupled to the hybrid switch converting data between a telephony data format used by the telephone network and a packet data format used by the packet network.
The invention includes a method for converting data between a telephony data format and a packet data format. The method comprises: converting data from the telephony data format to the packet data format; and converting data from the packet data format to the telephony data format.
For the method, converting data from the telephony data format to the packet data format comprises: receiving data in the telephony data format; accumulating in digital logic hardware the data to obtain a telephony data frame; selecting in digital logic hardware a digital signal processor from an array of digital signal processors; passing the telephony data frame to the selected digital signal processor; transcoding in the selected digital signal processor the telephony data frame to obtain a coder-decoder data frame; and encapsulating in the selected digital signal processor the coder-decoder data frame to obtain data in the packet data format.
For the method, converting data from the packet data format to the telephony data format comprises: receiving data in the packet data format; accumulating in digital logic hardware the data to obtain a packet data frame; resequencing in digital logic hardware the packet data frame to obtain a coder-decoder data frame; selecting in digital logic hardware a digital signal processor from an array of digital signal processors; passing the coder-decoder data frame to the selected digital signal processor; decoding in the selected digital signal processor the coder-decoder frame to obtain a telephony data frame; passing the telephony data frame to digital logic hardware; and encapsulating in digital logic hardware the telephony data frame to obtain data in the telephony data format.
Moreover, the above objects and advantages of the invention are illustrative, and not exhaustive, of those which can be achieved by the invention. Thus, these and other objects and advantages of the invention will be apparent from the description herein or can be learned from practicing the invention, both as embodied herein and as modified in view of any variations which may be apparent to those skilled in the art.